Sheet stacking machine



L. 5. BROWN 2,625,394

SHEET STACKING MACHINE Jan. 13, 1953 Filed April l9, 1949 14Sheets-Sheet l L. 5. BROWN SHEET STACKING MACHINE Jan. 13, 1953 14Sheets-Sheet 2 Filed April 19, 1949 Jan. 13, 1953 5, BROWN 2,625,394

Y I SHEET STACKING MACHINE Filed April 19, 1949 1 4 Sheets-Sheet s" 1953L. s. BROWN 232 :5394 SHEET STACKING MACHINE Filed April 19; 1949 14Sheets-Sheet 4 01 Q 0 q v n t N Q 3 I\ 3nventor Jan. 13, 1953 14Sheets-Sheet 5 Filed April 19, 1949 I k I Jan. 13, 1953 3 BROWN SHEETSTACKING MACHINE l4 Sheets-Sheet 6 Filed April 19, 1949 1953 L. s. BROWNSHEET STACKING MACHINE l4 Sheets-Sheet '7 Filed April 19, 1949 65Zhwentor L4 WEE/V65 .5. 5 90 w v Jan. 13, 1953 L. s. BROWN SHEETSTACKING MACHINE 14 Sheets-Sheet 8 Filed April 19, 1949 lllllllllllGttorneg' (/85 Inventor- 1953 1.. 5. BROWN SHEET STACKING MACHINE FiledApril 19, 1949 14 Sheets-Sheet 9 VT L (Ittomeg 1953 L. 5. BROWN SHEETSTACKING MACHINE l4 Sheets-Sheet 13 Filed April 19, 1949 31mm or u/ 5m:5. BROWN.

Ctttomeg Jan. 13, 1953 1.. 5. BROWN 2,525,394

SHEET STACKING MACHINE Filed April 19, 1949 14 Sheets-Sheet 14 W IHHH P1 1533 I Jnneutor LA WEE/V65 J, 5E0 w/v.

Gttorneg Patented Jan. 13, 1953 sneer STACKING MACHINE Lawrence S.Brown, Massapequa, N. Y., assignor to The Sperry Corporation, acorporation of Delaware Application April 19, 1949, Serial N0. 88,441 4Claims. (Cl. 271--79) This invention relates to a machine for stacks inglarge sheets of flexible material, such as paper, which are deliveredthereto at high speed, as from a high speed rotary printer. H

It: :has for an object to provide a machine of the above type which iscapable of progressively stopping; the forward motion of the sheets andlaying them horizontally on a stack in smooth unwrinkled condition.

Another object is to provide a machine of the above type which iscapable of being adjusted to operate with sheets of various sizes and atvarious delivery speeds. Y

Another object is to provide, in a machine of the above type, controlledejector means for ejecting a single sheet for purposes of inspection.

A more specific objectis to provide a stacking devicewhich is capable ofoperating with high speed rotary presses.

Various other objects and advantages will be apparent as the nature ofthe invention is more fully disclosed. I

The novel features which are characteristic of this invention will bebetter understood by referring to the following description, taken incon- 2 Fig. 12 is a section similar to Fig. 11 showing the parts in adifierent position;

Fig. 13 is a section taken on the line l3-l3 Fig. 12 illustrating adetail of the ejector mechnection with the accompanying drawings in,

which a specific embodiment thereof has been set forth for purposes ofillustration. In the drawings: Fig. 1 is a horizontal section of astacking machine embodying the present invention, taken on the linel-'-I of Fig. 2;

Fig. 2 is a vertical longitudinal section through the machine, taken onthe line 2-2 of Fig. 1; 1

Fig. 3 is a broken horizontal section similar to i Fig. 6 is a verticalsection similar to Fig. 2 but on an enlarged scale, showing the sheetreceiving end of the machine;

Fig. 7 'is a vertical section similar to Fig.. 6 showing the stackingend of the machine;

Fig. 8 is a vertical section similar to Fig. showing the parts in adifferent position with the lower end of the ramp broken away; I

Fig. 9 is a detail view showing the lower end of the ramp; D

Fig. 10 is a broken horizontal section showing the sheet conveyor andgripper bars;

Fig. 11 is an enlarged section taken on the line ll-Il of Fig. 3illustrating the timingv adJustment mechanism;

speed of the sheet.

anism;

Fig. 14 is a section taken on the line I4-l4 of Fig. 12 showing thetiming cam;

Figs- 15 and 16 are sections taken on the lines I5-l 5 and I6|6,respectively, of Fig. 11;

Fig. 17 is a vertical section through the transfer chain taken on theline I'|-I7 of Fig. 10 but on a larger scale;

Figs. 18, 19 and 20 are sections taken on the lines l8l8, I9l9 and20-20, respectively, of

Fig. 17 showing the construction of the gripper bars;

Fig. 21 is a detail section taken on the line 2l-2l of Fig. 22;

Fig. 22 is a section taken on the line 2222 of Fig, 21;

Fig. 23 is a section taken on the line 23-23 of Fig. 21;

Fig. 24 is a horizontal section taken on the line 2424 of Fig. 22;

Fig. 25 is a section similar to Fig. 22 showing the parts in a diflerentposition;

Fig. 26 is a section similar to Fig. 23 showing the parts in a differentposition;

Fig. 2'7 is a diagrammatic view of the drive mechanism for the transferand conveyor chains;

Fig. 28 is a section taken on the line 28-28 of a Fig. 29 is a sectiontaken on the line 29-29 of Fig. 27;

Fig. 30 is a detail sectional view of the drive mechanism;

Figs. 31 and 32 are detail perspective views showing parts of thetransfer mechanism.

Referring first to Figs. 1 and 2, a web 35 is delivered at high speedfrom a machine such as a rotary printer over a delivery roll 36, betweena pair of guide rolls 31, and around an idler roll 38, thence arounddrive roll 39 to a cutting station comprising a stationary knife 40 anda rotary knife 4| mounted on a rotor 42. The rotation of the rotor 42 istimed to cut the web 35 into sheets 34 of the desired length.

From the cutting station the sheets 34 are fed to a sheet conveyor shownas a set of belts 43 travelling at a speed higher than that of the weband passing around rollers 44 to 48.

The belts 43 deliver the leading edge of each of the sheets 34 to agripper bar which at that time is in aposition to grip said edge and istravelling at a speed somewhat less than the forward The gripper bars asthey advance from right to left as seen in Figs. 1 and 2 are deceleratedby the mechanism to be described until they are brought to rest at apoint over the left hand side of the stack whereupon the gripper barsare opened to release the out sheets 34 onto the stack. The gripper bars50 travel in an endless circuit and after releasing the sheets areaccelerated until they are brought to their proper speed for grippingthe next sheet.

An air blast 52 from a row of nozzles 53 is directed against the uppersurface of the sheet 3 after the sheet has been gripped by a gripper bar90 so as to cause the sheet to be removed rapidly from the belts 0i; andto fall onto the previous sheet on a ramp 53. Due to the fact that thegripper bars 50 are moving at a slower speed than the belts 43 the sheetimmediately forms a catenary loop as it is gripped by the bars 50. Theair blast 52 is directed onto this loop and serves 1 to pull thetrailing end of the sheet from the conveyor belts 43. A second air blast54 from a row of nozzles 58 is directed against the lower end of thesheet to cause the same to lie fiat against the ramp 55. As thesuccessive sheets are gripped by gripper bars which are progressivelydisplaced, the sheets lie in shingled formation, the trailing edge ofthe last sheet extending below the edge of the preceding sheet and lyingagainst vacuum pad 9i which is carried by the ramp "-55 and whichassists in holding the lower edge of the sheet flat against the ramp.

The stack 5i rests on a platform 00 which is progressively lowered bychains 6i as the stack increases in thickness, so that the top of thestack remains at substantially the same elevation.

Referring to Figs. 2, 3, 5, 6, a and 9, the ramp 55 is shown ascomprising a frame '55 hinged at the top' over a roller Gii'and carryingacross bars 07, 88 and 00. The crossbar 61 is fixed to the framers andcarries a plurality of spaced vertical I rods 50 on which the sheetsrest. The cross bar 0 8'is adjustable along the frame '05 and may besecured in adjusted position by bolts TI. The cr'dss bar 08 carries aplurality of spaced vertical rods I2. i V w H v} The cross bar 09 ismounted for vertical adjustment on aslide '53 which is slidably mountedon the frame 06 and is secured in adjusted position by bolts I4. Theslide I3 also carries the vacuum box 5! having a perforated top plate I5over which the lower edge of the cut sheets fall. A plurality of spacedvertical rods iii are mounted on the cross bar 09. A plurality ofsimilar spaced bars H are mounted on a cross bar I0 attached to theslide I3. The central rods are rigidly mounted on the cross bars as bywelding. The rods at the two sides of the ramp, however, are madeadjustable so that the ramp may be adjusted to various w'idthsof web.For this purpose the various rods at the two sides of the ramp aremounted on U-shaped brackets 80, BI and 82 (Figs. 8 and 9) "which are,respectively, slidable along the cross bars 61, 00 and 69 and may be setin adjusted position by means of set screws. The inclination of the rampmay be adjusted by means of a bar 05 attached to the frame I55 andsliding in a strap 7 86 which is clamped to a stationary bracket 01 bymeans of a bolt 00. I

A vacuum pad as is positioned to engage the trailing end of the bottomsheet as it leaves the 4 ramp 59 to disengage the sheet for release ontothe stack 5I.

Referring now to Figs. 17 to 20, each gripper bar 50 comprises a pair ofend plates I00 carrying rollers IOI which travel in tracks I02 attachedto the frame of the machine and forming an endless path; A transversetube I03 is attached to the end plates I00. This tube carries anelongated stationary jaw member I04 at its lower side and at its topcarries a toothed bar I05.

Movable jaw members I06 are mounted on brackets I01 which are journalledto rotate about a transverse tube I08 which is also secured to the endplates I00. The brackets I01 carry arms I09 having a plurality of spacednotches I I0 on their under sides to receive pins H5 to which are attached springs III. The notches IIO permit adjustment of the springtension.

Brackets II2 are also journalled about the tube I08 and have at theirupper ends pawls I I3 which are adapted to engage the teeth in the barI05.

The upper ends of the springs I I I are attached to pins II4 on theupper ends of the brackets H2. The brackets I01 and H2 are slidablealong the tube I08 for purposes of adjustment in accordance with thewidth of the sheet to be gripped, and the engagement of the upper ends II3 of the brackets I I2 with the teeth in the bar I 05 secures the samein adjusted position.

A shaft I20 is journalled in the end plates I00 and extends throughholes I2I in the brackets I I2 which have suflicient clearance with theshaft --I20 to permit the necessary pivotal movement of the brackets II2about the tube I08.

The shaft I20 carries pawls I22 which engage rollers I25 carried by thearms I09 and serve to depress the arms I09 when the shaft I20 is rovtated into the position shown-in Fig. 19, thereby opening the movablejaw members I00 against tension of the springs III. Theshaft I20 isactuated by rollers I23 carried on arms I24 attached to the shaft I20.

As shown'in Fig. 8, when the gripper bar 50 approaches'its grippingstation in its path around the circularportion MP of the track I02, the

' roller I23 engages'a stationarycam I28 which depresses the roller asitadvances in a clockwise direction around the cam I28'so that thegripper jaws 100 are opened before the gripper bar reaches its lowerposition. The roller r23 then rides over the surface of an adjustablecam I30 which retains the jaws in open position until therollerreaches'the end of the foam I30 at which point the roller isreleased'and the jaws are closed by the springs I I I.

As shown in Figs. 12 and 14, the cam I30 is in the forin'of a steppedcylinder which is mounted V on a shaft I 3 I for rotation by a worm I32and worm gear I33 from a transverse shaft I34 which extends across themachine and as shown in Fig. 3 and is provided at it's end with anactuating arm I36 having a handle I31. The arm I36 may be latched invarious positions bfzicljustment by means of aspring' pin I38 engagingholes in a plate I39 (Fig.4) A similar adjustable cam I30 is mounted ateach side of the machine for actuating'the rollers I23 on the two endplates I00 and are adjusted in unison by the shaft I34. The

purpose of the adjustable cams I30 is to adjust the gripping position ofthe gripper'bars 50 in accordance with the size of the sheet beingstacked. The transverse positions of the various movabte jaws I06 "isalso adjusted in accordance "with the width of the sheet 34 and theyare' so disposed as to pass between the various conveyor shafts belts 43(Figs. 1 and 10). As indicated in Fig. 10, the conveyor belt rollerpulleys 44 are adjustably mounted on a shaft I45 which, as shown in Fig.

v8, is'mounted on a sliding bracket I50 having a rack II adjusted bymeans of a gear I52 for varying the position of the discharge ends ofthe belts 43 as desired.

Referring to Fig. 6, the sheet 34 is fed on the belts 43 under astationary guide plate-I55. The plate I55 is provided over certain ofthe belts 43 with a pair of holesin which balls I 56 rest. These ballsare held in a cage I51 and are adapted to ride on the sheets 34 beingfed and to hold the same in contact with the belts 43. In order to ejecta sheet for purposes of inspection, a rock'lever I60 is provided at eachside of the machine (Figs. 11 to 16) and is pivoted about a shaft I6Iextending across the machine. Each lever I60 is provided with a lower(cam) surface I62 to engage the rollers I23 of the gripper bars 50. Whenthe surface I62 is in raised position as shown in Fig. 11, there issufiicient clearance to allow the rollers I23 to remain in theirgripping positions. When the surface I62 .is tilted downwardly, however,as shown in Fig.

12, it engages the rollers I23 and depresses the same to release theclamping jaws I06 as the gripper bars 50 progress from right to left asseen in Figs. 11 and 12.

The lever I60 is actuated by a link I64 which is secured at its free endto a block I65 and is normaLy held in its right-hand position as seen inFigs. 11 and 12 by a spring I65. A transverse shaft I61 extends acrossthe machine through elongated slots in the links I64 and carries camsI68 which are adapted to engage the blocks I65 when the shaft I61 isrotated in either direction and thereby shift the blocks I65 and linksI64 to the left. An actuating handle I may be provided to actuate theshaft I61.

In order to cause the machine to eject only a single sheet a latch isprovided in the form of a member I1I pivoted at I12 to the lever I60 andadapted when the lever is depressed to engage a plate I13 carried on afixed bracket I14. A spring I is positioned to hold the member I1I inlatched position. The member I'll also carries a release pawl I11 whichis adapted to be engaged by the roller I23 as the roller passesthereunder, so that the roller elevates the pawl about the pivot I12 andreleases the latch I1I from beneath the plate I13, thereby allowing thespring I66 to return the parts to their original positions so that theroller I23 on the following gripper bar is not actuated. When the rollerI23 is actuated by the surface I62 to open the clamping jaws I06 thesheet of paper which is held by the clamping jaws is released and fallsonto the floor so that it can be inspected without stopping the machine.

The gripper bars 50 are fed along the machine by means of a transferchain I85 (Figs. 1 and 3) on each side of the machine which passes oversprockets I86 and I81, and a conveyor chain I88 on each side of themachine which passes over wheels I89 and I90 (Fig. 1). The transfer andconveyor sprockets I86 and I89 are mounted on I9I and I92, respectively,which are driven by means to be described. The drive for the chains I85and I88 i illustrated in Fig. 27 as comprising a drive shaft I95 whichis driven at a constant speed by a source of power not .shown. The shaftI95 carries a gear I96 meshing with a gear I91 carried on a shaft I93.The .shaft I98 carriesa gear .I99meshing with a gear 200 on a shaft Icarryin an arm 202 in which a, pin 203 is journalled. I

The pin 203 carries a gear 204 to, which is attached an arm 205 carryinga roller 206 displaced from the axis of the pin 203 the same distance asthe displacement of the axis of the pin 203 from the axis of the shaftMI. The gear 204 meshes with an internal stationary gear 201 to form anepicyclic train which is so designed that, as the'gear 204 is drivenaround the gear 201, the roller 206 oscillates in a straight linein adirection normal to the plane of the paper as seen in Fig. 27 and with alinear harmonic motion.

The roller 206 engages a slot 2l0 in the forked end of a lever 2I2 whichis attached to a shaft 2I3 and thus serves to rock the shaft 2I3 withoscillating motion which is very nearly rotary harmonic.

The shaft 2I3 carries a segment gear 2I4 (Fig. 28) meshing with asegment gear 2I5 attached to a shaft 2I6 and so arranged that the shafts2I3 and 2I6 operate in opposite directions and by an amount determinedby the relative radii of the segment gears 2I4 and 2I5. The segment gear2I4 also meshes with a segment gear 2I1 carried by a shaft 220 which isconnected by segment gears 22I, 222 tooscillate a shaft 223. The shaft223 carries a segment gear 224 meshing with a segment gear 225carriediby a gear 226 forming one side of a differential 221.

The shaft 2I6 also carries a segment gear 230 meshing with a segmentgear 23I on a shaft 232 carrying a segment gear 233 meshing with asimilar gear 234 carried by a gear 235 forming one side of adifferential 236. The connections are such that the input gears 226 and235are oscillated in synchronism and in the same direction but bydifferent amounts which may be adjusted by suitable selection of thesegment gears 230 and 23I.

The shaft I98 carries at its far end a gear 238 meshing with a gear 239carried by a gear 240 forming the opposite side of the differential 236.A gear MI is driven by the gear 239 and is attached to agear 242 formingthe second side of the differential 221. Hence the gears 240 and 242 ofthe two differentials are rotated in opposite directions and bydifferent speeds which depend upon the ratios of the gears 238, 239 and24I.

The spider 245 of the differential 236 is attached to a shaft 243carrying a gear 241 meshing with a gear 248 carried by a shaft 249which, through beveled gears 250 and 25I, drives the shaft I9I. Thegears 241 and 248 may be changed for varying the drive ratio. The spider253 of the differential 221 is attached to a shaft 254 which, throughbeveled gears 255 and 256, drives the shaft I92. The shaftsI9I and I92are thus driven in the same direction, but at different speeds each ofwhich varies with thetimed motion introduced by the oscillation of thegears 235 and 226, and the average rates of which differ in accordancewith the various gear ratios. The gears are so selected that the maximumspeed of the transfer chain I is somewhat less than the rate of feed ofthe paper sheet 34, preferably between 60% and 85% of the linear rate offeed of such sheet, and the minimum speed of the transfer chain I85 isequal to the maximum speed of the conveyor chain I88. The

.minimum speed of the conveyor chain Iifll'is tioned variations :isequal tothe time; interval between delivery of successive sheets a to.the gripper bars. The mechanism for selectively connecting. vthegripper bars 56 to 'be-drivenbythetwo sets of I chains is illustrated inFigs..21 to26. Referring 'to these figures, each end plate Hill carriesvan .arm 2B0 having-a pairof. pinstzfil and 262 on -which two pairs-ofclamping jaws 263, 254. and 265, 266'are mounted. The jaws 263 .andZGflia-re interconnected by a pin 26? andslotlfiiito cause the jaws 283-andZM-When elevated tothe positions shown in Fig. 23 to engage a .feed pin2B9 carried by the conveyor chain 488, and. when retracted in theposition shown in Fig. 26. to release such pin. Similarly 'theclampingjaws 265 and 265 are interconnectedby a pin 21 [and slot 212 tocause thejaws to operate in unison so that when elevated as shown in Fig. 25 theyenagage a feed pin 213 carried-by the transfer chain A I85 (Fig. 21) andwhen retracted as shown in Fig. 22 they are released from said pin.

'For selectively actuating the twosets of clamp- "ing jaws a cam plate233 is provided which is pivoted about a pin 28G carried by the bracket-26D and carries a pairof lugs 282 and 283 (Fig. 31) which are adaptedto engage shoulders 284 and 285 on jaws 263 and 263, respectively, forretracting one of said jawsand advancingthe -'other as the cam plate 289is shifted about its axis. The cam plate is also provided with surfaces286 and 281 which contact the respective "shoulders 284 and 285 forlocking either the jaws 263 and 254 or the jaws 265 and 256 in elevatedpositions. The shoulders 2-S8'and 2B9on theplate 280 form stopstolimit'the movement thereof.

' In order to prevent the plate 238' from moving when not actuated byexternal means a-pointed cam surface 292 is provided engaging a roller293 mounted on an arm 2% which is pivoted to.

a pin 295 on the bracket 250 and is held inwardly by a spring 296. Theroller 293, riding over the pointed cam surface 232, looks the plate 286in either the position shown in Figs. 22 and 23 or "thepositionshown inFigs. 25 and 26. The connections are such that oneset of jaws engages-a-feed pin before the "other set of jaws has en- 'tirely released-itsfeed pin so as to avoid possibility of entirely releasing the gripperbar from *both chains during the shifting operation.

In order to shift the cam plate 280 'from'one position to the other, theplate is providedwith an arm 298 carrying. a roller 299 which engagessuitable stationary cam surfaces atthe appropri- -ateplaces along thepath of movement oi -thew gripper bars. As shown in Fig.5, theroller 299i-engages a stationary cam 38% whichlis adapted .to force'therollerdownwardly fcr shifting the iclamping jaws from :the transferchain to the rconveyor chain. at that apointand engages a stationary cam30! for shifting the clamping jaws from-the conveyor chain tothetransfer chain. uThese points are so selected thatat both points thefeed pins-of the two chainsare in alinement I and traveling at the-samespeed.

An adjustable cam E (Fig 7) controls-there- 'lease of the gripping jaws19S. .TI'his cam 38% is .:mounted on a slide 353 having a rack 357iengaged .by a gear 3ii8-mounted on a shaft 389 for purposes of adjustingthe point of release of the sheets by .the gripper bars. A handle 3) isprovided -(Figs. 3 and. '17) for-actuating the shaft 3:39. A spring pin3!! is carried in'the hub 3!.2 of the handle '3I0 for latching thehandle in selected l. positions.

edge of each sheeth34xinto which the web iscut is fed by the belts 4,3into the open jaws :of 1a gripper bar which is timed to receive thesameand at that instant is being advanced at nearly maximum speed by thetransfer chain 155. The gripping jaws then close to grip the, for andend o h s e t an th r pper barmm iately begins to slow dow .due to t esci lat n commoment i he rat o s ee o the trans er h n- When this cursthe heet 4 orms a 10.01 du to the di f ren n eed b ween th gr er b andthe belt a d s lew-n dcwnwerdlv-pv the a r t 2 i rm a sh n les s ack th"ram 5- A the ip er b r i d alo e b in ran er chai 8 and r ach s he ponts mi m m s ee o the ransfer ehein t shiiied 991 n o cha n 58 hic attha time i tra l n at ts ma i um ed, T gr e r is thereafter d ong b tcor e r at varying rates through several cycles until it momentarilybecomes stationary at the point of delivery where the sheet has beendrawn cornpletely over the stack 51. The gripping jaws are then releasedto drop-the stationary sheet. The gripper then continues its travel onthe conveyor chain until it is again shifted to the transfer chain whichoccurs after one ormore. cycles ,of travel and at an instant when theconveyor chain is. traveling at its maximum speed. Thereafter thetransfer bar is advanced through one or more cycles by the transferchain until itis again brought into sheet receiving position.

It is to be noted that each sheet is separately laid on the stack 5] andis separately .'br01 1 ht down from maximum speed to a condition of restbefore it is released onto the stack. Hence the device may be used forstacking very thin sheets of material such as tissue paper weight whichif not restrained would-tend to crumple if suddenly brought to restiromthe high speed of the travel ing web.

Obviously if the rate ofs peedof the webisnot too great the gripper barsmay be brought :frQm maximum speed to rest or nearly .so. by means of asingle chain in which event the transier me n s ma be m ted n t ent o vey h sp eds w er. ibis m ac to rate the speed of advance of --the gripperbars .from maximum speed. to a condition of rest during the smallinterval of time allowed between the presentation of successive sheetsto the stacker mechanism.

Various changes and -modifications may :be made as will be apparent-toa. person skilled in the art. '7

What is claimed is:

1. A machine for stacking sheets of flexible m i fed t r to in areid a vnci e'rr n. m r si gs p ura it o awarenesbers, means ad ancinss id ppinmembers i a ess ath n succes ion 1 m a shee acei ins stat on throu h a seet r le sin station back t t e sh re iving, station. said: -ad vancingmeans comprising a pair of conveyors operating in line in :theysamedirection, means driving each of said conveyors at a variablerate whichvaries cyclically between amaxirnum and a minimum rate .of speed, the.maximumrateof thefirst conveyor :being somewhat less than .the rate .ofadvance ofsaid procession, the minimum rate: of said first conveyor:being equalv to the maximum rate of said second conveyor, the minimumrate of said second conveyor being substantially zero speed, means onsaid first conveyor to advance said gripping members from said grippingstation to an intermediate point between said gripping station and saidreleasing station, means between the gripping station and theintermediate point for successively deflecting the trailing portions ofthe gripped sheets from the path of the succeeding sheets, means at saidintermediate point to transfer said gripping members from said firstconveyor to said second conveyor, means located at the point of minimumspeed of said second conveyor to cause said gripping members to releasesaid sheets and means in the said return path of said gripping membersto re-transfer the same to said first conveyor.

2. A stacking machine as defined in claim 1 in which the deflectingmeans comprise blower means located at a point beyond said grippingstation and arranged to remove the trailing ends of said sheets from thepath of the succeeding sheets, whereby said sheets are caused to hangdownwardly from said gripping members as they are advanced thereby.

3. In a stacking machine, as set forth in claim 1, an inclined ramppositioned beneath the path of travel of said gripping members betweensaid gripping station and said releasing station, means withdrawing thetrailing ends of said sheets from the path of succeeding sheets afterthe sheets have been gripped by said gripping members and causing saidsheets to fall downwardly upon said inclined ramp in shingled formation,whereby said sheets are pulled upwardly over said ramp by said grippingmembers as they advance to said discharge station, suction meansdisposed on said ramp to cause the trailing ends of said sheets to lieflat against said ramp.

4. A stacking machine as set forth in claim 1 in which each of thegripping members comprises a bar disposed transverse to the direction ofmovement of the conveyors and carrying a plurality of sheet clampingjaws, and has means associated with the bars for gripping bothconveyors, and there are cam means operative upon the gripping means anddisposed in their paths to cause the said means at one point to grip thefirst conveyor and simultaneously to release the grip on the secondconveyor, then at a succeeding point to release the grip on the firstconveyor and simultaneously grip the second conveyor and then at thesaid one point again to grip the first conveyor.

LAWRENCE S. BROWN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 533,444 Dejonge Feb. 5, 18951,156,903 Henderson Oct. 19, 1915 1,540,687 Feistel et a1 June 2', 19252,226,674 Seybold Dec. 31, 1940 2,300,863 Bamford Nov. 3, 1942 2,332,863Luehrs Oct. 26, 1943 2,381,430 Belluche Aug. 7, 1945 2,474,997 WormserJuly 5, 1949 FOREIGN PATENTS Number Country Date 19,447 Great BritainAug. 24, 1909 473,337 Great Britain Oct. 7, 1937 513,206 Great BritainOct. 6, 1939

